The general construction and arrangement of welding masks or shields are not new. Typical prior art welding masks or shields are shown in various prior United States patents including the following: R. Malcolm, U.S. Pat. No. 1,904,993, issued Apr. 25, 1933; N. Anderson, U.S. Pat. No. 3,257,667, issued Jan. 28, 1966; J. N. Simpson et al, U.S. Pat. No. 3,458,865, issued Aug. 5, 1969; and Walters et al, U.S. Pat. No. 4,354,279, issued Oct. 19, 1982.
These prior art masks are generally of similar construction and comprise a shield section, preferably curved to conform somewhat to the face of the wearer. The shield section is preferably molded as a unit from an opaque, plastic, lightweight, stiff material. The shield is normally worn on the head of the user and includes some type of head band so it may be pivoted upwardly when not in use and easily moved to a face-protecting position.
When in a face-protecting position, the shield is faced forwardly of the wearer's face and extends around the side of the wearer's head so as to cover the head. The shield is usually provided with an enlarged, rectangular opening within which is mounted a lens assembly consisting of a plurality of panes, including, for example, an outer pane formed from a transparent material such as glass, an inner pane formed of similar material but which is tinted, colored or otherwise treated to eliminate the transmission of harmful radiation to the eyes of the wearer. Such radiation may be produced when contact is made between an energized welding rod and a work piece. The panes are usually separated by a gasket and are of a peripheral dimension conforming generally to the shape of the pocket-like viewing port in the shield but slightly undersized so that they may be easily assembled therein.
Typically, the panes of the lens assembly are oftentimes supported in the rectangular opening by means of a spring clip. The deficiencies of such an arrangement have been noted in U.S. Pat. No. 4,354,279. The mounting means described in that patent combines the insert and a spring clip into a unitary piece. An insert is provided which effectively blocks external light rays which might produce a corona or halo effect interiorly of the welding mask. A spring clip is provided which has horizontal leg portions pressing the insert against the lens pack.
The Walters et al design is admirably suited for providing an adequate corona barrier. Nevertheless, while the positioning of the lens pack is in a protected position to prevent penetration of harmful rays to the interior of the mask, the use of a spring clip is not totally satisfactory as a mounting means. The spring clip is somewhat clumsy and awkward to assemble and disassemble and can be inadvertently engaged to release the lens pack. What would be an improvement would be a system that is easy and quick to assemble and disassemble and will allow the lens pack to be removed only when a deliberate action by the operator is made but which cannot be accomplished unintentionally. Elimination of any wire which can come loose and harm the user is, of course, highly desirable.